2: PARALLEL LINES (of straight lines) lying in the same plane but never meeting no matter how far extended. Some problems that may happen if these lines weren't parallel is that the floors might collapse/crack or the floors will damage the walls they are aligned with.

3: TWO CONGRUENT OBJECTS Either of two angles formed by two intersecting lines and lying on opposite sides of the point of intersection. My picture is of trees and all trees are different so there really isn't a problem.

4: Vertical Angles Either of two angles formed by two intersecting lines and lying on opposite sides of the point of intersection. The person might have made these designs to show that both sides of the line are equal when dealing with shapes that need to be exactly aligned.

5: Perpendicular Lines Perpendicular lines are lines that intersect at right angles. Well, in my picture, there is already an accident having to due with Perpendicular lines and if the lines weren't perpendicular; the car would be fine

6: INTERSECTING LINES An intersection is a single point where two lines meet or cross each other. If the lines didn't intersect in my picture, then people would most likely have a harder time having to travel in an orderly manner and will probably have a dangerous accident

7: SUPPLEMETARY LINES An intersection is a single point where two lines meet or cross each other.Two Angles are Supplementary if they add up to 180 degrees. If these angles were not supplementary, then the shape/line would not be a straight line and could cause serious design flaws if the measurements were not correct.

8: DIFFERENT PROPORTIONS Comparative relation between things or magnitudes as to size, quantity, and number.

9: ADJACENT Two angles that share the same vertex and one side. The two sides that are not shared form a larger angle

10: SIMILARITY Geometric figures having the same shape but different sizes.

11: TWO DIMENSIONAL Having the dimensions of height and width only

12: Surface Area The total area of the faces and curved surface of the a solid figure.

13: Pythagoras Pythagoras of Samos is one of the most famous mathematicians of all time. He was born in Samos, Greece in 569 BC. His most famous discovery was the Pythagorean theorem which is still used in geometry today.

14: Diameter A straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.

15: Three Dimensional Having, or seeming to have, the dimension of depth as well as width and height.

16: VOLUME The quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains.